Officers called off the search for Julie Middleton after finding the body in open water at Queslett Nature Reserve at the rear of the Asda supermarket at around 3pm today.
West Midlands Police said: "Whilst the body has not yet been formally identified, it is believed to be that of 73-year-old Julie.
"Her family has been informed and are being supported by specially trained police officers.
"The death is not being treated as suspicious."
She is believed to have left her house on Queslett Road in Great Barr at some point overnight on Sunday and was reported missing just after 9am yesterday.
Teams of specialist officers had been searching areas of open ground and woodland in the Great Barr area.